The present invention relates generally to a steam humidifier used in HVAC systems in buildings.
Since 1985, most steam humidifiers used steam injection manifolds that contain nozzles in the duct distributor pipes. The nozzles can be in the form of plain holes placed along the length of the pipe. This arrangement has been found to be unsatisfactory, since it allows the condensate to flow out of the holes into the airstream along with the steam. By using nozzles instead of plain holes that feed off the center of the pipe where the steam is hottest and driest, condensate is prevented from getting out with the steam.
However, it is labor intensive to install the nozzles into the steam distributor pipes, since holes must be drilled before the nozzles can be inserted, into them and if a mistake is made on capacity, it is very difficult, if not impossible, to add nozzles to increase capacity Exceeding the capacity of the nozzles results in a very heavy steam flow, which takes longer to evaporate in the airstream. In some cases, the nozzles used have been made of plastic and can come loose and leak or blow out of the distributor pipes.
To shorten the distance it takes for the steam to evaporate in the airduct, the number of distributor pipes have been increased to spread out the steam output over the entire cross-sectional area of the airduct. However, because there is now more surface of the distributor pipes exposed to the cold airstream, the result is usually more condensate production (which can be as much as 50% loss of the steam to condensate), loss of steam output, and heat-gain to the air in the airduct, which could be as much as 15xc2x0 F. If the building is under cooling load, this heat-gain to the airstream will be detrimental to maintaining the building temperature.
In view of the above, there is, therefore, a need for a steam humidifier that avoids the shortcomings of the prior art.
It is an object of the present invention to provide a steam humidifier where the steam distributor pipes are provided with pressure variable apertures, instead of standard nozzles, that adjust their output to meet the demand.
It is another object of the present invention to provide a steam humidifies where the steam distributor pipes are installed to the manifold with slip fittings without tools, allowing the pipes to be easily disassembled and cut to fit the height of the airduct.
It is still another object of the present invention to provide a steam humidifier where the distributor pipes can be cut in the field to fit the height of the existing airduct without any detrimental effect to its steam distribution capacity.
It is another object of the present invention to provide a steam humidifier that can easily be retrofitted to switch to a different means of steam production, including direct steam, steam heat exchanger, electric coil, or gas-fired heat exchanger.
It is still another object of the present invention to provide a steam humidifier where the steam distributor pipes are insulated and where the nozzles are fed from the central part of the pipes where steam is hottest and driest, thereby minimizing production of condensate.
It is another object of the present invention to provide a steam humidifier where the contact ratio of steam to air is substantially 100%.
In summary, the present invention provides a humidifier for providing moisture to an airstream within an airduct, comprising a base manifold configured for being secured to a side of the airduct, the base manifold including a steam inlet valve and a condensate drain valve; and a distributor pipe secured to the base manifold and configured to extend into the airduct, the distributor pipe being in communication with the base manifold.
The present invention also provides a humidifier for providing moisture to an airstream within an airduct, comprising a base manifold configured for being secured to a side of the airduct; a heat-exchanger disposed within the base manifold configured to boil water disposed within the base manifold to steam; and a distributor pipe secured to the base manifold and configured to extend into the airduct, the distributor pipe being in communication with the base manifold.
The present invention further provides a nozzle for dispensing moisture into an airstream, comprising a pipe having a first end for connecting to a source of steam and a closed second end; first and second slots disposed opposite each other and longitudinally along a major portion of the length of the pipe; and the pipe being subject to flexing such that the slots open up in response to the steam being introduced thereinto, thereby to release steam in the airstream.
The present invention also provides a method for humidifying an airstream in a duct, comprising providing a nozzle configured to provide a sheet pattern of spray; disposing the nozzle in the airstream; connecting the nozzle to a source of steam; directing the steam sheet pattern transversely to the direction of the airstream such that maximum surface area of the sheet pattern is presented to the airstream.
These and other objects of the present invention will become apparent from the following detailed description.